Synthesis of perfluoroalkylated pentacenes and evaluation of their fundamental physical properties

Abstract

Symmetrical and unsymmetrical pentacenes carrying two perfluoroalkyl (Rf) chains, at the 6 and 13 positions, were synthesized from easily available pentacene-6,13-quinone via facile three or four step reactions. After extensive evaluation, it was clearly found that the control of both the electron density of the aromatic rings on the pentacene core and molecular alignment in the crystalline state nicely affected their physical properties. Thus, we successfully prove in this article that (1) their anti-oxidation ability was significantly enhanced due to a decrease in the HOMO and LUMO energy and (2) a distinct difference in charge-transporting properties was observed between the symmetrical and unsymmetrical pentacenes.

PAH/PAH(CF3)n Donor/Acceptor Charge‐Transfer Complexes in Solution and in Solid‐State Co‐Crystals

“…[22,23,25,26,46,[49][50][51] In addition to their spectroscopic and electrochemical characterization, nearly two-thirds of them have also been studied by single-crystal X-ray diffraction and have had their EAsd etermined by low-temperature gas-phase photoelectron spectroscopy.T hese strong electron acceptors, with EAst hat range from 1.8 to 3.2 eV,a re listed in Supporting Information Ta ble S1.T his table also includes information about the 16 other PAH(CF 3 ) n derivatives reported by others that were prepared by more conventional, multi-steps ynthetic methods. [28,[52][53][54][55][56][57][58][59][60][61][62][63] We herein report as olution, solid-state, and computational study of nine (PAH) x /(PAH(CF 3 ) n ) y donor/acceptor (D/A) chargetransfer (CT) complexes that involve the four PAHd onors and six PAH(CF 3 ) n acceptors shown in Figure 1a nd Figure2,r espectively.T heir abbreviations, ionization energies (IEs), EAs, E 1/2 (+ /0) or E 1/2 (0/À)e lectrochemical potentials, and longest wavelength CT l max valuesa re listed in Table 1. [64][65][66] These are the first D/A CT complexes with PAH(CF 3 ) n acceptors to be studied in detail.T he nine D/A combinations werec hosen to allow several comparisons to be made in order to providen ew insights about controlling PAHD /A interactions and the structures of CT co-crystals.…”

Experimental and DFT Studies of the Electron‐Withdrawing Ability of Perfluoroalkyl (RF) Groups: Electron Affinities of PAH(RF)n Increase Significantly with Increasing RF Chain Length

“…In another example, Yamazaki and co‐workers prepared a series of 6,13‐pentacene(R F )(R F ′) derivatives with R F and R F ′ groups=CF 3 , C 2 F 5 , n ‐C 4 F 9 , n ‐C 6 F 13 , n ‐C 8 F 17 , and n ‐C 10 F 21 . Unfortunately, their electrochemical reductions were also irreversible, precluding the determination of E 1/2 (0/−) potentials for a precise comparison of these R F groups’ electron‐withdrawing ability (see Supporting Information for more details) …”

“…[7][8][9][10][11] The number of carbon atoms in these straight-chain substituents commonly varies from 1t o8by single integers. Chemists take advantage of the fact that lengthening the R F chain length can significantly alter the solubilities, [12][13][14] gas-phase acidities, [15] and both solid state and liquid crystal packing motifs [16][17][18] of homologous series of compoundsw ith one or more R F substituents. Much lessi sk nown about how much the electron-withdrawinga bility changesa st he R F chain is sys-tematically lengthened, and how much those changes can affectm easurable electronic properties of ah omologous series of compounds.…”

“…[20] In another example, Yamazaki and co-workers preparedaseries of 6,13-pentacene(R F )(R F ')d erivatives with R F and R F ' groups = CF 3 ,C 2 F 5 , n-C 4 F 9 , n-C 6 F 13 , n-C 8 F 17 ,a nd n-C 10 F 21 . [12] Unfortunately,t heir electrochemicalr eductions were also irreversible,p recluding the determination of E 1/2 (0/À)p otentials for ap recise comparison of these R F groups'e lectronwithdrawing ability (see Supporting Information for more details). [12] In 2012, we published an experimental and DFT study on the effect of R F chain length on the gas-phase electron affinities (EAs) of fullerene compounds with ap air of R F groups attachedt ot he para-positions of aC 60 hexagon (i.e.,aseries of 1,7-C 60 (R F ) 2 derivatives with R F = CF 3 ,C 2 F 5 , n-C 3 F 7 , n-C 4 F 9 ,a nd n-C 8 F 17 ).…”

“…[12] Unfortunately,t heir electrochemicalr eductions were also irreversible,p recluding the determination of E 1/2 (0/À)p otentials for ap recise comparison of these R F groups'e lectronwithdrawing ability (see Supporting Information for more details). [12] In 2012, we published an experimental and DFT study on the effect of R F chain length on the gas-phase electron affinities (EAs) of fullerene compounds with ap air of R F groups attachedt ot he para-positions of aC 60 hexagon (i.e.,aseries of 1,7-C 60 (R F ) 2 derivatives with R F = CF 3 ,C 2 F 5 , n-C 3 F 7 , n-C 4 F 9 ,a nd n-C 8 F 17 ). [21] The effects weres mall but statistically significant:t he EAs varied from 2.920(8) eV for C 60 (CF 3 ) 2 to 2.985(8) eV for C 60 (n-C 4 F 9 ) 2 to 3.010(8) eV for C 60 (n-C 8 F 17 ) 2 ,a ss hown in Figure S1 in the Supporting Information.…”